We shall continue our work on the structure and function of yeast ribosomes. We have a collection of cold-sensitive mutants that will be analyzed genetically and biochemically. The structure of yeast ribosomes will respect to their post-translational modifications and possible changes in mutants will be examined. Antibiotics will be screened and mode of action analyzed, we are presently working on hygromycin B and some related antibiotics that inhibit eukaryotic translation. Antibiotic resistant :utants will be sought and analyzed genetically and biochemically. Since we have radioactive drugs, we will continue to probe the interaction between antibiotics and the ribosome. BIBLIOGRAPHIC REFERENCES: D. G. Schindler and J. Davies. Specific cleavage of ribosomal RNA caused by alpha sarcin. Nucleic Acids Res. 4, 1097 (1977). E. Cundliffe and J. Davies. Inhibition of initiation, elongation and termination of eukaryotic protein synthesis by trichothecene fungal toxins. Antimicrob. Ag. Chemother. 11, 491 (1977).